The present invention relates to effectively using radio resources in a UMTS (Universal Mobile Telecommunications System), which is a European type IMT-2000 system, and more particularly, to techniques employed at the transmitting side (transmitter) to configure the size information of data to be received by the receiving side (receiver), and how much size information is to be transmitted.
The UMTS (Universal Mobile Telecommunications System) is a third generation mobile communications system that evolved from the European GSM (Global System for Mobile Communications) system, with the purpose of providing further improved mobile communications service based upon a GSM core network and W-CDMA (Wideband Code Division Multiple Access) technology.
FIG. 1 depicts a typical UMTS network (100) architecture. The UMTS broadly consists of user equipment (UE 110), a UMTS Terrestrial Radio Access Network (UTRAN 12), and a core network (CN 130). The UTRAN consists of one or more radio network sub-systems (RNS 121, 122), and each RNS consists of one radio network controller (RNC 123, 124) and one or more base stations (Node Bs 125, 126) that are managed by the RNC. The Node B, being managed by the RNC, receives data sent from a physical layer of the UE via the uplink and transmits data to the UE via the downlink, to thus act as an access point of the UTRAN with respect to the UE. The RNC handles the allocation and management of radio resources, and acts as an access point with the CN.
FIG. 2 depicts a radio interface protocol architecture based upon a 3GPP radio access network specification between the UE and the UTRAN. The radio interface protocol of FIG. 2 is divided horizontally into a physical layer, a data link layer, and a network layer, and is divided vertically into a user plane for data transmissions and a control plane for transfer of control signaling. Namely, the user plane is the region in which traffic information of the user (such as voice, IP (Internet Protocol) packets and the like) is transferred, while the control plane is the region in which control information (such as the interface of the network, maintaining and managing calls, and the like) is transferred. The protocol layers of FIG. 2 may be divided into a first layer (L1), a second layer (L2), and a third layer (L3) based upon the lower three layers of an open system interconnection (OSI) model that is a well-known in communications systems.
Each layer depicted in FIG. 2 will now be described in more detail. The first layer (L1) is a physical layer (PHY) that provides information transfer service to upper layers by using various radio transmission techniques, and is connected to a medium access control (MAC) layer that is located thereabove via a transport channel through which data travels between the MAC layer and the physical layer. In particular, the data blocks delivered between the MAC layer and physical layer via the transport channel are called transport blocks.
The MAC layer provides services to a radio link control (RLC) layer, which is an upper layer, via a logical channel. In general, when information of the control plane is transmitted, a control channel is used. When information of the user plane is transmitted, a traffic channel is used.
The MAC layer is sub-divided into a MAC-b sub-layer, a MAC-d sub-layer, a MAC-c/sh sub-layer, and a MAC-hs sub-layer, according to the type of transport channel that is managed.
The MAC-b sub-layer manages a BCH (Broadcast Channel), which is a transport channel handling the broadcasting of system information.
The MAC-d sub-layer manages a dedicated channel (DCH), which is a dedicated transport channel for a specific terminal. Accordingly, the MAC-d sub-layer of the UTRAN is located in a serving radio network controller (SRNC) that manages a corresponding terminal, and one MAC-d sub-layer also exists within each UE.
The MAC-c/sh sub-layer manages a common transport channel, such as a forward access channel (FACH) or a downlink shared channel (DSCH), which is shared by a plurality of terminals. In the UTRAN, the MAC-c/sh sub-layer is located in a controlling radio network controller (CRNC), and one MAC-c/sh sub-layer exists for each cell because the channels shared by all UEs within a cell are managed.
The MAC-hs sub-layer manages a HS-DSCH (High-Speed Downlink Shared Channel), which is a shared transport channel that transmits high-speed data on the downlink.
The radio link control (RLC) layer supports reliable data transmissions, and performs a segmentation and concatenation function on a plurality of RLC service data units (RLC SDUs) delivered from an upper layer. When the RLC layer receives the RLC SDUs from the upper layer, the RLC layer adjusts the size of each RLC SDU in an appropriate manner upon considering processing capacity, and then creates certain data units when header information added thereto. The created data units are called protocol data units (PDUs), which are then transferred to the MAC layer via a logical channel. The RLC layer includes a RLC buffer for storing the RLC SDUs and/or the RLC PDUs.
There is a radio resource control (RRC) layer at a lowermost portion of the L3 layer. The RRC layer is defined only in the control plane, and handles the controlling of logical channels, transport channels, and physical channels with respect to establishment, reconfiguration, and release of radio bearers (RBs). The radio bearer service refers to a service that the second layer (L2) provides for data transmission between the terminal and the UTRAN in order to guarantee a predetermined quality of service by the UE and the UTRAN. And in general, the radio bearer (RB) establishment refers to regulating the protocol layers and the channel characteristics of the channels required for providing a specific service, as well as respectively setting substantial parameters and operation methods.
When the RRC layer of a particular UE and that of the UTRAN are connected to allow RRC messages to be sent and receive therebetween, that UE is said to be in RRC connected state. If there is no such connection, that UE is said to be in idle state.
Hereafter, the characteristics of an E-DCH (Enhanced Dedicated Channel) will be explained. The E-DCH is a transport channel used when a particular UE is to transmit high-speed uplink data. To support high-speed uplink data transmission, a MAC-eu sub-layer is located in the MAC of the UTRAN and UE, respectively. The MAC-eu sub-layer of the UE is positioned below the MAC-d sub-layer. The MAC-eu sub-layer of the UTRAN is located in the Node B. The E-DCH is a transport channel that is currently being introduced in 3GPP, and thus its particulars have not yet been agreed upon at this time.
A method of delivering the size information of a transport block from the transmitting side to the receiving side will now be explained. One transport block is delivered via one transport channel in (during) one transmission time interval (TTI). When there is a transport block(s) to be transmitted, the MAC of the transmitting side delivers to the physical layer, one or more transport blocks in units of TTI. The physical layer of the transmitting side performs encoding on the transport blocks received from the MAC, and performs transmission to the physical layer in the receiving side. Here, to aid the physical layer in the receiving side for accurately decoding the encoded data, the transmitting side also transmits to the receiving side, transport format (TF) information together with the encoded data. Upon receiving the TF information transmitted from the transmitting side, the physical layer of the receiving side uses this TF information to perform decoding of the received data and reconfigures the transport blocks. These reconfigured transport blocks are then delivered to the MAC of the receiving side in units of TTI.
The TF information includes the various attributes that one transport channel has. These attributes in the TF information can be divided into two categories, referred to as ‘attributes of the semi-static part’ and ‘attributes of the dynamic part.’ The attributes of the semi-static part referred to the TF information that can change slowly because it is transmitted by RRC messages. The attributes of the dynamic part refer to the TF information that can change quickly because it is transmitted by units of TTI or units of radio frames. Here, the attributes of the dynamic part are delivered (transported) by means of a TFCI (Transport Format Combination Indicator). The Transmitting side transmits the TFCI to the receiving side via the control field of the physical channel.
In the related art, transport block size and transport block set size are the representative types of attributes of the dynamic part. Here, a transport block set is defined as a set of transport blocks that are transmitted in a TTI.
As in FIGS. 3, 4A, and 4B, one transport block is defined as one MAC PDU (Protocol Data Unit) that includes a MAC SDU (Service Data Unit) and a MAC header, and one or more transport blocks may be delivered during one TTI. Here, the length of the transport blocks transmitted during one TTI are the same. Thus, the length of the transport block set is a multiple of the length of a transport block.
The RRC performs in advance, the configuration of the set comprising the transport block length values and the transport block set length values through the RRC messages. Thus, each time a transport block is transmitted in units of TTI, the transmitting side selects one transport block length and one transport block set length, among those in the configured set, and delivers these values to the receiving side.
In the related art, each transport block has its own MAC header. One reason for using this scheme is because the transport block length (that includes the MAC header length) is used to inform the TF information. However, in this scheme, if there are two or more transport blocks during one TTI, and the transmitted MAC header contents are the same, the redundancy in MAC header content is problematic. That is, MAC headers having the same content are unnecessarily used redundantly. Thus, the related art suffers from disadvantages due to the waste of radio resources caused by MAC header redundancy.
A gist of the present invention involves the recognition by the present inventors of the drawbacks in the related art.
The present invention provides a transport block transmission method that divides the length of the transport block, to be transmitted from the transmitting side to the receiving side, into a header length and a length of the transport block excluding the header length, and transmits these via respectively different channels or respectively different messages. Also, the header length included in the transport block is fixed, and the header length and the length of the transport block excluding the header length are transmitted with respectively different frequency or regularity.